Q: Over Christmas we stayed at a friend's house that has underfloor heating, and I was really impressed. I would like to install it at home but there are two problems. One is that the floors in our bungalow are solid concrete, which makes them very cold (which is why the underfloor heating sounds so attractive). Can the heating be laid on top of this, or would the floors have to be dug up?

And secondly, we don't have a gas supply or boiler, we currently use night storage heaters on Economy 7 – is electric underfloor heating possible?

PF, Norfolk

A: If you have solid ground floors, then underfloor heating (UFH) is one of the most comfortable forms of room heating. This is because the solid floor acts as a thermal store – it doesn't just keep your feet warm, but it smooths out fluctuations in the room temperature. With other forms of heating, such as warm air or radiators, if you leave the back door open for five minutes, all the heated air escapes. But with UFH the structure of the building itself stays warm, regardless of air temperature changes.

People with underfloor heating tend to be rather evangelical about it, which used to make me suspicious, but I have had electric UFH in my own house for six years now, and I have joined their ranks – I wouldn't want to be without it. I installed the Devi electric cabling system (01359 242400,gaiacs.com) and run it on the Economy 7 off-peak tariff. The combined timer and thermostat allows it to be switched on during the day as well if needed, but this is rarely necessary as my exposed brick floors keep the heat in until evening, when it's time to light the wood-burning stove. My total annual electricity bill – for a detached house in exposed countryside – is around £1,200, which I think is pretty good.

The cabling itself is relatively inexpensive. The main expense comes from excavating the floors, filling the space with insulation, and then the brick (or concrete) finish. UFH is pointless unless you excavate and insulate first – otherwise the heat would simply be conducted downwards to warm the earth below your home. There are systems that comprise foam insulation slabs on top of the existing floor, with tiles or laminate flooring on top of this, but there will be little thermal mass to store heat, so these will require a constant heat input, and are not suitable for the Economy 7 tariff.

Your best option would probably be to do one room first – say your lounge – and see how much it costs and how you like it. Then do the other rooms later. The kitchen will be the most expensive room, as the worktops and base units will have to be taken out and then refitted.

Drain drama

Q: I have had to have my main drain unblocked. The TV pictures of the interior clearly show roots growing through quite large cracks which have occurred in the pipe. The contractor has suggested that an internal sleeve could be inserted to avoid the cost of digging up the old pipes and relaying the whole drain. This would reduce the bore from six inches (150mm) to more like four inches (100mm).

Do you have any thoughts about the suitability of a sleeve (presumably some sort of plastic) and the efficiency of a reduced bore? The property is about 50 years old and located in an area of clay subsoil. The distance involved is about 30ft (10m).

AR, by email

A: I am puzzled about where you got the idea that a drain-lining sleeve would reduce the internal bore from 150mm to 100mm, and I can't believe that an experienced drainage contractor would have told you this. GRP (glass-reinforced plastic) lining is only a few millimetres thick, and the reduction in bore size would be negligible.

A specialist drain-lining company would carry out its own CCTV survey (costing around £75), and clean out the inside of the pipe, using a "spinner" to cut off protruding tree roots. Most cracks can be covered by the lining sleeve; the only time relining would not be feasible is when there is a displacement – i.e. one section of pipe has moved in relation to another. Expect to pay around £80 per metre plus VAT.